Lynn Museum has closed temporarily while its new Seahenge gallery is completed to tell the story of Bronze Age Lynn and showcase the 4,000-year-old timbers found at nearby Holme.

The timbers have been on quite a journey since they were excavated from the shoreline in 1999. The preserved circle of oak posts was lifted and initially taken to Flag Fen Bronze Age Centre in Cambridgeshire for preliminary preservation and studying, before the Mary Rose Trust in Portsmouth received them for conservation work in 2003.

The new gallery at Lynn Museum will display half of the 55 timbers as they were found and also a reconstruction of what they might have looked like when built. The central up-turned tree stump is still at Portsmouth – its size means conservation work on it is taking longer.

“The museum has all of them, but after thorough public consultation we decided to display just half of them so that we also had the space to tell the story behind them,” said Hannah Jackson, Project Manager for the museum’s £1.2million redevelopment.

“On one side we’ve got a 22-metre long mural of a Bronze Age landscape. We’re trying to show people that Seahenge wasn’t on the coast when it was built – it was actually slightly inland on salt marsh.”

The timbers themselves are shown with a backdrop of the modern beach setting as they were found. They’re set within plinths so that visitors can see both the cut side of the lengths and the bark.

The new gallery offers various theories as to what the timber circle, made of trees felled in 2049BC, could have been used for.

“The main theory supported by archaeologists is that it was to do with excarnation,” said Hannah. “That is, bodies would have been laid out there for birds and animals to pick the bones clean. This theory is supported by finds at other sites, but the fact is we don’t know what Seahenge was for because there were no accompanying finds.”

Excarnation has been suggested because of jumbles of bones discovered at other sites that suggest they had been transported there rather than coming from a buried whole body.

The upturned stump that was situated at the centre of the Seahenge circle could have held a body for this purpose. Such an inversion could have been symbolic, too, suggested Hannah, referring to the world of the dead rather than the living. The use of the wood and leaving the bark on might even suggest the henge was related to the worship of a woodland deity.

Part of the mural showing a Bronze Age setting. Mural designed by uglystudios.com and hand painted by John Stokes. Photograph by Andi Sapey

The conservation process has taken a long time. At Flag Fen, the timbers were sprayed and salt water drawn out, before conservators at the Mary Rose Trust began to apply the same processes to them as have been used on the famous Tudor warship.

“The timbers were immersed in a synthetic wax, polyethylene glycol, or PEG,” said Hannah. “Then they were vacuum freeze-dried. That is, they were taken down to a temperature of –20C and placed in a vacuum, where the ice turns to vapour straight from its solid state, so that the liquid has less opportunity to damage the timber.”

Now visitors will be able to see the wooden henge in the well-preserved state in which it was found.

“They’ve survived very well after 4,000 years!” added Hannah.

The Bronze Age gallery is the second part of Lynn Museum’s Heritage Lottery funded redevelopment, which has already seen the museum’s Chapel gallery refurbished. The Chapel gallery tells the story of the area from the Iron Age onwards with archaeological finds and other exhibits.